NPR's Ron Elving Previews 2016 Presidential Race

The presidential field grew more crowded this week as three more Republicans launched bids and others, including Jeb Bush, continue their unofficial campaigns. At the same time, eyes are on Democratic frontrunner Hillary Clinton and the growing controversy over donations to her family's foundation. We talk to NPR News' Senior Washington Editor Ron Elving about the decisive issues in this race and whom we should be watching and why.